Electrically heated thermal latch safety device



July M; 1934. 'N. H. KIMBALL ELECTRICALLY HEATED THERMAL LATCH SAFETY DEVICE Filed Jan. 8, 1954 Patented July 17, 1934 UNITED STATES PATENT GFFIE Norman H. Kimball,

Application January 8,

1 Claim.

This invention relates to an electrically heated thermal safety device and is an improvement over my Patent No. 1,956,902, dated May 1, 1934.

One object of this invention is to provide a safety device to be placed between the control motor and fuel control valve which connects the control motor to the valve control valve of gas or oil burning furnaces.

I is customary with gas or oil burning furnaces to have a thermostatic control apparatus to control the heat of the furnace by opening or closing the fuel supply valve. If the electric current be broken in any manner to the apparatus it will stop working. If the valve was open when it did stop the flow of fuel would keep on entering the furnace as the valve would remain open with very serious results. There have been cases where this has occurred where the furnace and boiler have been completely ruined and the building set afire as well.

With my invention attached to the control motor and fuel supply valve the above would never happen, for as soon as the electric current was broken an expansible yoke would begin to cool and contract and move a latch bar off of a catch which will disconnect the control motor from the control valve by allowing the latch bar to fall to its lowest position which allows the valve to close and stop the flow of fuel to he furnace as the motor pull on the valve has been released.

With these and other objects in view my invention consists of the following construction of parts to be hereinafter described and claimed.

In the accompanying drawing forming a part of this specification and in which corresponding parts are denoted by like reference characters is illustrated the preferred form of embodiment of the invention capable of carrying the same into practical use, it being understood that the invention is not necessarily limited thereto, as various changes in its shape and general assemblage of its parts may be resorted to without departing from the principles of the invention, and the right is therefore reserved to make all changes and modifications which will fall within the scope of the invention.

Referring to the drawing:

Figure l is a view showing a part of a controlling apparatus of a furnace with my invention attached thereto.

Fig. 2 is a fragmentary side view of latch bar 1.

Fig. 3 is a fragmentary section view showing the latch bar in its lowest position.

Salt Lake City, Utah 1934, Serial No. 705,707

Fig. 4 is a vertical section view showing the latch bar in its upper unlatched position.

Fig. 5 is a vertical section view showing the latch bar in its upper latched position.

The reference character A denotes a casing for an electric switch, B a control motor, C a casing for the fuel supply valve, D my invention attached to the control motor and fuel sup ply valve and E a transformer for transforming the electric current to the heating unit 13.

The invention comprises a casing having a thread on each end thereof. On the upper end is threaded a cap 3 having an eye 4 thereinto which one end of a chain 5 is secured, the other end of the chain is secured to the crank 6 of the control motor B.

A cap '7 is threaded onto the lower end having an aperture therein into which is threaded one end of a pipe 8 the other end of the pipe projecting into the casing.

In the lower end of the pipe 8 is placed a plug 9 which has an aperture 10 therein through which passes a latch bar 1. A pin passing through the latch bar forms lugs ll which come into contact with the inner edge of the plug 9 and prevent the latch bar falling out of the casing when it is in its lower disconnected position.

The reference character 12 denotes an expansible york which is secured by one end to the upper end of the pipe 8 by rivets 18 or other means. Secured to the yoke 12 is an electric heating unit 13 which is controlled by an electric current passing through the cables 22 and transformer E from the electric switch. When the electric current is passing through the heating unit it expands the yoke to move it outward away from the upper end of the latch bar 1 so that the latch bar may be latched over the catch 14 by the pressure of a spring 23 which holds the notch 15 over the catch 14 thus locking the two sections together. The spring 23 is secured to the inside of the pipe 8 by rivets 24 or other means. The catch 14 is made in the pipe by cutting and pressing in its side wall.

The upper end of the latch bar has a projection 16 thereon to which the free end of the yoke engages when the yoke cools to draw the notch 15 off of the catch 14 when the latch bar 1 is to be lowered relatively to the casing or to disconnect the control motor from the valve.

One end of a chain 19 is attached to the fuel valve lever 20 and the other end is connected to the latch bar 1 so when the casing and latch bar are coupled together as shown in Fig. 4 and the control motor is operated the valve 2 will be opened or closed by the movement of the control motor. And in the event that in any manner that the electric current should be broken to the heating unit it will cool and contract and in doing so it will move the notch 15 oiT of the catch 14 as shown in Fig. 5, thus disconnecting the valve lever 20 from the control motor so the valve may close.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

A thermal latch safety device comprising 2, casing having means on one end for supporting the same, a pipe extending into said casing through its other end, said pipe having a catch adjacent its inner end, a latch bar extending into and being movable relative to said pipe and having a projection thereon adapted to engage said catch when the latch bar is in its innermost position, a spring in said pipe urging said bar towards said catch, a thermally expansible member coacting with the inner end of said latch bar when cold to hold it out of engagement with said catch and operable when heated to release said bar whereby the spring will urge said bar into engagement with said catch to latch the bar in its innermost position and means for electrically heating said expansible member.

NORMAN H. KIMBALL. 

